Resilient electrical contact assembly

ABSTRACT

An insulating support plate has an aperture therethrough for receiving an electrical contact pin reciprocally movable in the aperture. One end of the aperture is threaded. A coil spring around the pin has the coils at one end formed to match the threads of the aperture and are threaded into the aperture. The remainder of the spring has a larger pitch for resilience and the other end frictionally engages the pin and abuts against a shoulder on the pin so that the pin is secured to the support by the spring and is resiliently movable relative to the support.

Unlted States Patent 1 1 3,805,006

mark 1451 Apr. 16, 1974 [5 RESILIENT ELECTRICAL CONTACT 321,933 7/1885 Pieper 339/67 x ASSEMBLY FOREIGN PATENTS OR APPLICATIONS Inventor: Richard Clark, Kokomo, 263,321 1/1927 Great Britain 310/247 Assigneez General Motors Corporation 818,292 8/1959 Great Britain 3l0/247 Demon Mlch' Primary ExaminerJames R. Scott [22] Flledi Oct 13, 19 2 Assistant Examiner-William J. Smith No: Attorney, Agent, 0! Firm-Warren D. 57 B TRACT [52] [1.8. CI ..200/290, 310/247, 339/217 R, A 8

39/255 R An Insulating support plate has an aperture there- [51] Int Cl H011] 1750 r 39/40 through for receiving an electrical contact pin recipro- [58] Fie'ld 41 61 46 166 D cally movable in the aperture. One end of the aperture 200/166 BE 5 3 is threaded. A coil spring around the pin has the coils R 55 67 R at one end formed to match the threads of the aperture and are threaded into the aperture. The remain- [56] References Cited der of the spring has a larger pitch for resilience and the other end frictionally engages the pin and abuts UNITED STATES PATENTS against a shoulder on the pin so that the pin is secured 1 1 3 to the support by the spring and is resiliently movable arvey e a 3,376,444 4/l968 Eaton et al. 310/247 X relatlve to the Support 457,109 8/1891 Criggal 339/67 X 1 Claim, 2 Drawing Figures RESILHENT ELECTRICAL CONTACT ASSEMBLY This invention relates to a resilient electrical contact assembly.

It is desired, particularly in devices for testing a printed circuit assembly, to use a fixture for making temporary electrical connections with the test circuit. Such devices have comprised an insulating support plate containing resilient contact pins press fit into holes in the support and electrical leads soldered to the contact pins. Previously the contact pins comprised expensive subassemblies which were difficult to mount to the support board so that initial set-up or replacement of pins was expensive and time consuming.

It is therefore a general object of this invention to provide an electrical contact assembly which is inexpensive and wherein contact pins are easily installed in a support member.

Another object of the invention is to provide a resilient electrical contact which is threadedly secured to a support member. I

The invention is carried out by providing an apertured support member with screw threads formed within the aperture, an elongated contact pin slidably disposed-within the aperture, and a coil spring surrounding the contact pin having one end threaded into the aperture and the other end coupled with the contact pin for retaining and biasing the pin. The above and other advantages will be made more apparent from the following specification taken in conjunction with the accompanying drawings wherein like reference numerals refer to like'parts and wherein;

FIG. 11 is a partially sectioned view of a contact assembly according to the invention and FIG. 2 is an exploded view of the assembly of FIG. 1.

Referring to the drawings, an insulating support plate 110 contains a bore or aperture 12 extending therethrough. One end of the bore is formed with screw threads 14. A coil spring 16 has coils 18 at one end formed at a pitch and diameter which complements the threads 14 in the support member. The remainder of the spring preferably is formed with a larger pitch to provide substantial resilience and travel. The terminal portion 20 of the spring opposite the coils 18 is turned inwardly a small amount to form in effect a coil of reduced diameter. An elongated contact pin 22 has a shank portion 24 of a diameter just small enough to freely slidably fit within the aperture 12 and the spring 116. One end of the contact pin 22 is chamferred and the other end has an enlarged conical head 26 which provides a shoulder 28 and further provides a contact point for connection with the test point of a circuit. Shapes other than a conical point are employed as required.

The assembly of the elements preferably is accomplished by sliding the spring 16 over the shank of the contact pin 22 until the terminal portion 20 engages the shoulder 28. Since the terminal portion is turned in, it frictionally engages the shank 24 to secure the spring and pin elements together. The pin is then inserted into the aperture 12 and the coils l8 threaded into the threads 14 of the support member to complete the assembly. Preferably the contact is connected to an electrical conductor by means of a conventional post connector which slides over the chamferred top of the contact pin.

As a specific example, the support plate may be one-half inch thick plexiglass with an aperture of 0.0937 inch counterbored and tapped with a thread having a pitch of 32 per inch. The spring 16 is formed with a 0.095 inch inside diameter with six coils 18 formed to a pitch of 32 per inch to conform to the threads in the support plate. The spring has a total of fourteen turns and a length of 0.75 inch. The contact 22 is of stainless steel and has a shank diameter of 0.092 inch and a length of about 1.5 inch.

It will thus be seen that the resilient electrical contact assembly is exceptionally simple in structure, easy to assemble, rugged, readily replaced and inexpensive.

The embodiment of the invention described herein is for purposes of illustration and the scope of the invention is'intended to be limited only by the following claims.

What is claimed is:

11. A resilient electrical contact assembly comprising, in combination:

a support member having a guide bore formed therein, at least a portion of the bore having a screw thread,

an elongated contact pin disposed within the guide bore for reciprocal movement therein, the contact pin having an enlarged portion defining a shoulder facing the support member and spaced therefrom, and

means for resiliently securing the contact pin to the support member comprising a coil spring surrounding a portion of the contact pin and having one end formed into coils having a pitch and diameter complementing the screw threads in the bore and being threadedly engaged in the bore for securing the spring to the support member, the other end of the spring abutting the shoulder on the contact pin and having a tumed-in terminal portion in frictional engagement with the pin, whereby the contact pin is resiliently biased relative to the support member and is secured thereto by the spring. 

1. A resilient electrical contact assembly comprising, in combination: a support member having a guide bore formed therein, at least a portion of the bore having a screw thread, an elongated contact pin disposed within the guide bore for reciprocal movement therein, the contact pin having an enlarged portion defining a shoulder facing the support member and spaced therefrom, and means for resiliently securing the contact pin to the support member comprising a coil spring surrounding a portion of the contact pin and having one end formed into coils having a pitch and diameter complementing the screw threads in the bore and being threadedly engaged in the bore for securing the spring to the support member, the other end of the spring abutting the shoulder on the contact pin and having a turned-in terminal portion in frictional engagement with the pin, whereby the contact pin is resiliently biased relative to the support member and is secured thereto by the spring. 